1. Field of the Invention
The present invention relates to a device for retaining a connecting rod of a spine fixator on pedicular screws previously anchored in the pedicles of the lumbar vertebrae of a backbone.
2. History of the Related Art
Several types of devices for retaining the connecting rods of spine fixators are known.
Retaining devices exist, which are mounted on the connecting rod before it is positioned on the pedicular screws anchored in the lumbar vertebrae. These devices are constituted by rings having an internal profile identical to that of the rod in order to be traversed thereby. Nuts enable the rod to be secured inside the rings. These retaining devices require perfect alignment of the pedicular screws in the sagittal and frontal plane. In fact, if the alignment is not proper, connection with the rod is impossible unless the latter is deformed to recover the angular shift. Deformation of the rod does not facilitate slidable adjustment and positioning of the retaining devices before fixation of the rod on the pedicular screws.
Other retaining devices are mounted as and when needed on the pedicular screws anchored in the pedicles of the lumbar vertebrae. These devices require considerable dexterity of the surgeon to assemble all the elements of the spine fixator on the pedicular screws.
None of the retaining devices described heretofore enables surgeons to choose the manner of assembling the fixator on the pedicular screws, i.e. either positioning the connecting rod secured to the retaining devices, or assembling as the operation is being carried out.
It is a particular object of the present invention to overcome these drawbacks.
The purpose of the retaining devices according to the invention is to allow surgeons to choose the best adapted assembly of the fixator on the pedicular screws depending on the surgical difficulties encountered.